Polypropylene fibres

ABSTRACT

A polypropylene fibre including at least 80% by weight of a first isotactic polypropylene produced by a metallocene catalyst, and from 5 to 20 by weight of a second isotactic polypropylene produced by a Ziegler-Natta catalyst.

[0001] The present invention relates to polypropylene fibres and tofabrics produced from polypropylene fibres.

[0002] Polypropylene is well known for the manufacture of fibres,particularly for manufacturing non-woven fabrics.

[0003] EP-A-0789096 and its corresponding WO-A-97/29225 discloses suchpolypropylene fibres which are made of a blend of syndiotacticpolypropylene (sPP) and isotactic polypropylene (iPP). Thatspecification discloses that by blending from 0.3 to 3% by weight ofsPP, based on the total polypropylene, to form a blend of iPP-sPP, thefibres have increased natural bulk and smoothness, and non-woven fabricsproduced from the fibres have an improved softness. Moreover, thatspecification discloses that such a blend lowers the thermal bondingtemperature of the fibres. Thermal bonding is employed to produce thenon-woven fabrics from the polypropylene fibres. The specificationdiscloses that the isotactic polypropylene comprises a homopolymerformed by the polymerisation of propylene by Ziegler-Natta catalysis.The isotactic polypropylene typically has a weight average molecularweight Mw of from 100,000 to 4,000,000 and a number average molecularweight Mn of from 40,000 to 100,000, with a melting point of from about159 to 169° C. However, the polypropylene fibres produced in accordancewith this specification suffer from the technical problem that theisotactic polypropylene, being made using a Ziegler-Natta catalyst, doesnot have particularly high mechanical properties, particularly tenacity.

[0004] WO-A-96/23095 discloses a method for providing a non-woven fabricwith a wide bonding window in which the non-woven fabric is formed fromfibres of a thermoplastic polymer blend including from 0.5 to 25 wt % ofsyndiotactic polypropylene. The syndiotactic polypropylene may beblended with a variety of different polymers, including isotacticpolypropylene. The specification includes a number of examples in whichvarious mixtures of syndiotactic polypropylene with isotacticpolypropylene were produced. The isotactic polypropylene comprisedcommercially available isotactic polypropylene, which is produced usinga Ziegler-Natta catalyst. It is disclosed in the specification that theuse of syndiotactic polypropylene widens the window of temperature overwhich thermal bonding can occur, and lowers the acceptable bondingtemperature.

[0005] WO-A-96/23095 also discloses the production of fibres from blendsincluding syndiotactic polypropylene which are either bi-componentfibres or bi-constituent fibres. Bi-component fibres are fibres whichhave been produced from at least two polymers extruded from separateextruders and spun together to form one fibre. Bi-constituent fibres areproduced from at least two polymers extruded from the same extruder as ablend. Both bi-component and bi-constituent fibres are disclosed asbeing used to improve the thermal bonding of Ziegler-Natta polypropylenein non-woven fabrics. In particular, a polymer with a lower meltingpoint compared to the Ziegler-Natta isotactic polypropylene, for examplepolyethylene, random copolymers or terpolymers, is used as the outerpart of the bi-component fibre or blended in the Ziegler-Nattapolypropylene to form the bi-constituent fibre.

[0006] EP-A-0634505 discloses improved propylene polymer yarn andarticles made therefrom in which for providing yarn capable of increasedshrinkage syndiotactic polypropylene is blended with isotacticpolypropylene with there being from 5 to 50 parts per weight ofsyndiotactic polypropylene. It is disclosed that the yarn has increasedresiliency and shrinkage, particularly useful in pile fabric andcarpeting. It is disclosed that the polypropylene blends display alowering of the heat softening temperature and a broadening of thethermal response curve as measured by differential scanning calorimetryas a consequence of the presence of syndiotactic polypropylene.

[0007] U.S. Pat. No. 5,269,807 discloses a suture fabricated fromsyndiotactic polypropylene exhibiting a greater flexibilty than acomparable suture manufactured from isotactic polypropylene. Thesyndiotactic polypropylene may be blended with, inter alia, isotacticpolypropylene.

[0008] EP-A-0451743 discloses a method for moulding syndiotacticpolypropylene in which the syndiotactic polypropylene may be blendedwith a small amount of a polypropylene having a substantially isotacticstructure. It is disclosed that fibres may be formed from thepolypropylene. It is also disclosed that the isotactic polypropylene ismanufactured by the use of a catalyst comprising titanium trichlorideand an organoaluminium compound, or titanium trichloride or titaniumtetrachloride supported on magnesium halide and an organoaluminiumcompound, i.e. a Ziegler-Natta catalyst.

[0009] EP-A-0414047 discloses polypropylene fibres formed of blends ofsyndiotactic and isotactic polypropylene. The blend includes at least 50parts by weight of the syndiotactic polypropylene and at most 50 partsby weight of the isotactic polypropylene. It is disclosed that theextrudability of the fibres is improved and the fibre stretchingconditions are broadened.

[0010] It is further known to produce syndiotactic polypropylene usingmetallocene catalysts as has been disclosed for example in U.S. Pat. No.4,794,096.

[0011] Recently, metallocene catalysts have also been employed toproduce isotactic polypropylene. Isotactic polypropylene which has beenproduced using a metallocene catalyst is identified hereinafter as miPP.Fibres made of miPP exhibit much higher mechanical properties, mainlytenacity, than typical Ziegler-Natta polypropylene based fibres,hereinafter referred to as ZNPP fibres. However, this gain in tenacityis only partly transferred to non-woven fabrics which have been producedfrom the miPP fibres by thermal bonding. Indeed, fibres produced usingmiPP have a very narrow thermal bonding window, the window defining arange of thermal bonding temperatures through which, after thermalbonding of the fibres, the non-woven fabric exhibits the best mechanicalproperties. As a result, only a small number of the miPP fibrescontribute to the mechanical properties of the non-woven fabric. Also,the quality of the thermal bond between adjacent miPP fibres is poor.Thus known miPP fibres have been found to be more difficult to thermallybond than ZNPP fibres, despite a lower melting point.

[0012] WO-A-97/10300 discloses polypropylene blend compositions whereinthe blend may comprise from 25% to 75% by weight metallocene isotacticpolypropylene and from 75 to 25% by weight Ziegler-Natta isotacticpolypropylene copolymer. The specification is fundamentally directed tothe production of films from such polypropylene blends.

[0013] U.S. Pat. No. 5,483,002 discloses propylene polymers havinglow-temperature impact strength containing a blend of onesemi-crystalline propylene homopolymer with either a secondsemi-crystalline propylene homopolymer or a non-crystallising propylenehomopolymer.

[0014] EP-A-0538749 discloses a propylene copolymer composition forproduction of films. The composition comprises a blend of twocomponents, the first component comprising either a propylenehomopolymer or a copolymer of propylene with ethylene or anotheralpha-olefin having a carbon number of 4 to 20 and the second componentcomprising a copolymer of propylene with ethylene and/or an alpha-olefinhaving a carbon number of 4 to 20.

[0015] It is an aim of the present invention to broaden the thermalbonding window of miPP fibres. It is a further aim of the invention toprovide non-woven fabrics of miPP fibres exhibiting improved mechanicalproperties, in particular tenacity.

[0016] It is known that polypropylene fibres, and non-woven fabrics madeof polypropylene fibres, tend to feel rough to the touch. It is also anaim of the present invention to improve the softness of miPPpolypropylene fibres.

[0017] The present invention provides a polypropylene fibre including atleast 80% by weight of a first isotactic polypropylene produced by ametallocene catalyst, and from 5 to 20 by weight of a second isotacticpolypropylene produced by a Ziegler-Natta catalyst.

[0018] The polymeric fibre may preferably include from 85 to 95% byweight of the first isotactic polypropylene and from 5 to 15% by weightof the second isotactic polypropylene.

[0019] The polypropylene fibre may generally include from 0 to 15% byweight, more preferably from 0 to 10% by weight, of a syndiotacticpolypropylene (sPP). The addition of sPP can improve the softness of thefibres as well as the thermal bonding.

[0020] The second polypropylene produced by the Ziegler-Natta catalyst(ZNPP) may be a homopolymer, copolymer or terpolymer or a physical orchemical blend of such polymers.

[0021] The first polypropylene produced by the metallocene catalyst(miPP) is a homopolymer, copolymer, being either a random or blockcopolymer, or terpolymer of isotactic polypropylene produced by ametallocene catalyst or physical or chemical blend of such metallocenepolymers.

[0022] Preferably, the first polypropylene has a dispersion index (D) offrom 1.8 to 4. Preferably, the first polypropylene has a meltingtemperature in the range of from 130 to 161° C. for homopolymer and amelting temperature of from 80 to 160° C. for a copolymer or terpolymer.

[0023] The miPP preferably has a melt flow index (MFI) of from 1 to 2500g/10 mins. In this specification the MFI values are those determinedusing the procedure of ISC 1133 using a load of 2.16 kg a temperature of230° C.

[0024] More preferably, the first polypropylene homopolymer has an Mn offrom 30,000 to 130,000 kDa and the MFI may range from 5 to 90 g/10 minfor spunlaid or staple fibres.

[0025] Preferably, the second polypropylene has a dispersion index (D)of from 3 to 12. Preferably, the second polypropylene has a meltingtemperature in the range of from 100 to 169° C., more preferably amelting temperature of from 158 to 169° C. for homopolymer and a meltingtemperature of from 100 to 160° C. for a copolymer or terpolymer. Atypical melting temperature for homo ZNPP is 162° C.

[0026] The ZNPP preferably has a melt flow index (MFI) of from 1 to 100g/10 mins.

[0027] More preferably, the second polypropylene homopolymer orcopolymer has a MFI may ranging from 15 to 60 g/10 min for spunlaid or10 to 30 g/10 min for staple fibres.

[0028] The sPP is preferably a homopolymer or a random copolymer havinga RRRR racemic pentad content of at least 70%. The sPP may alternativelybe a block copolymer having a higher comonomer content, or a terpolymer.Preferably, the sPP has a melting temperature of up to about 130° C. ThesPP typically has two melting peaks, one being around 112° C. and theother being around 128° C. The sPP typically has an MFI of from 0.1 to1000 g/10 min, more typically from 1 to 60 g/10 min. The sPP may have amonomodal or multimodal molecular weight distribution, and mostpreferably is a bimodal polymer in order to improve the processabilityof the sPP.

[0029] The present invention further provides a fabric produced from thepolypropylene fibre of the invention.

[0030] The present invention yet further provides a product includingthat fabric, the product being selected from among others a filter,personal wipe, diaper, feminine hygiene product, incontinence product,wound dressing, bandage, surgical gown, surgical drape and protectivecover.

[0031] The present invention is predicated on the discovery by thepresent inventor that when blended with a major amount of miPP, even insmall concentrations, ZNPP causes improved thermal bonding of the miPPeven when the ZNPP is having a higher melting point than that of themiPP. Accordingly, when blending homopolymer miPP, which has a typicalmelting range of from about 130° C. to about 161° C., with homopolymerZNPP, which typically has a melting range of from about 159° C. to about169° C., fibres containing substantially high concentration of miPPexhibit superior thermal bonding properties.

[0032] The present invention will now be described by way of exampleonly with reference to the accompanying drawings, in which:

[0033]FIG. 1 is a stress/strain graph showing the relationship betweenstress and strain for a typical miPP and a typical ZNPP;

[0034]FIG. 2 is a graph showing the relationship between tenacity andcomposition for an miPP/ZNPP blend; and

[0035]FIGS. 3 and 4 are graphs showing the relationship between,respectively, elongation (%) at maximum drawing force and fibre tenacity(cN/tex) at maximum drawing force with respect to miPP amount for fibresproduced from blends of miPP and znPP.

[0036] It is known in the art that fibres with good thermal bondingproperties have a relatively large elongation at break and show aplateau region in the stress-elongation curve obtained by tensile tests.

[0037] Referring to FIG. 1, it may be seen for a typical miPP, whenformed into fibres the miPP has a high tenacity and therefore a highYoung's modulus (represented by the relatively steep slope of thestress/strain plot for miPP), and a relatively low elongation at break,typically around 200%. In contrast, for ZNPP, this exhibits a higherelongation at break, typically greater than 400% and a lower Young'smodulus, manifested by a relatively shallow slope in the stress/straingraph. Furthermore, at a strain of around 200% the ZNPP typicallyexhibits a plateau in the stress/strain graph. The higher fibre tenacityobtained with miPP results from the molecular orientation of a miPPdeveloped during spinning. It is very likely that the presence of ZNPPin miPP impedes development of that molecular orientation even atconcentrations around or below 20% wt. As a consequence, the mechanicalproperties of miPP fibres are very similar to those of ZNPP fibres evenif miPP is the main component of the blend or ZNPP concentration rangingfrom 20 to 50 wt % of ZNPP. As concentration of Znpp decreases below 20wt % some molecular orientation typical of miPP can progressivelydevelop in the fibre during spinning. Accordingly, the fibre tenacityprogressively increases and elongation at break progressively decreaseswhen ZNPP concentration decreases.

[0038] Referring to FIG. 2, this shows the relationship between tenacityand composition for an miPP/ZNPP blend in a polypropylene fibre. It maybe seen that for amounts of miPP of less than about 60 to 80% miPP inthe blend, the mechanical properties or the blend with respect totenacity are similar to that for ZNPP. At greater than about 90% miPP inthe blend, the tenacity is greatly improved, but this is offset byreduced elongation at break and as a consequence, tendency to have goodthermal bonding so that the high tenacity of fibre is not realised inthe resultant non-woven fabric. Accordingly, to achieve good mechanicalproperties in a non-woven fabric, typically the miPP/ZNPP blend includesfrom 5 to 20wt % ZNPP.

[0039] An industrial thermal bonding process for producing a non-wovenfabric employs the passage at high speed of a layer of fibres to bethermally bonded through a pair of heated rollers. This process thusrequires rapid and uniform melting of the surfaces of adjacent fibres inorder for a strong and reliable thermal bond to be achieved withoutdestroying the molecular orientation developed in the core of the fibre.The addition of ZNPP to the miPP despite not lowering the thermalbonding temperature of the fibres so as to broaden the thermal bondingtemperature range or “window” for the fibres, nevertheless increases theease of thermal bonding the fibres together. Thus the incorporation ofZNPP into miPP enables the maximum strength of the non-woven fabric tobe greatly increased as a result of this increased thermal bondformation between adjacent fibres.

[0040] The miPP employed in accordance with the invention has a narrowmolecular weight distribution, typically having a dispersion index D offrom 1.8 to 4, more preferably from 1.8 to 3. The dispersion index D isthe ratio Mw/Mn, where Mw is the weight number average molecular weightand Mn is the number average molecular weight of the polymer. The miPPhas a melting temperature in the range of from 130° C. to 161° C. Theproperties of two typical miPP resins or use in the invention arespecified in Table 1.

[0041] The addition of sPP to the miPP also has been found by theinventor to improve the softness of the fibres. As a result of a surfacerejection phenomenon, the inventor has found that the softness of thefibres may be increased using only small amounts of sPP, for examplefrom 0.3 wt % sPP in the sPP/miPP/ZNPP blend. Since the blending of sPPinto miPP permits a lower thermal bonding temperature to be employedthan would be employed for pure miPP fibres, and since lower thermalbonding temperatures tend to reduce the roughness to the touch of anon-woven fabric produced from the fibres, introducing sPP in accordancewith the invention into miPP improves the softness of the non-wovenfabric. The composition of a typical sPP for use in the invention isspecified in Table 1.

[0042] Furthermore, when sPP is incorporated into miPP to form blendsthereof, and when those blends are used to produce spun fibres, the sPPpromotes fibres having improved natural bulk, resulting in improvedsoftness of the non-woven fabric.

[0043] In addition, the use of miPP in blends with ZNPP and optionallysPP in accordance with the invention tends to provide fibres which canbe more readily spun as compared to known ZNPP fibres. Indeed, thesubstantial reduction of such long chains in the molecular weightdistribution of the miPP compared to standard ZNPP tends to reducebuilt-in stress during spinning thereby to allow in an increase in themaximum spin speed for the fibres of the miPP/ZNPP blends in accordancewith the invention.

[0044] The incorporation of sPP into the miPP of this invention to formblends thereof provides a broader thermal bonding window, allowingtransfer of the properties of the miPP fibres into the properties of thenon-woven fabrics produced from the blends. The thermal bondingtemperature of fibres produced from such blends is also slightly lower.The fibres and non-woven fabrics produced from the blends have increasedsoftness and the spun fibres have natural bulk as a result of theintroduction of sPP into the miPP of this invention. The fibres alsohave improved resiliency compared to known polypropylene ZNPP fibres asa result of the use of sPP. Furthermore, one use of miPP allows theproduction of finer fibres, resulting in softer fibres and a morehomogenous distribution of the fibres in the non-woven fabric.

[0045] Although it was known prior to the present invention to use asecond polymer in fibres, it has not heretofore been proposed to employZNPP in a blend with miPP for the production of fibres. Efficientthermal bonding of the fibres is required to transfer the outstandingmechanical properties of miPP fibres into non-woven fabrics. Inaddition, only around 5 weight percent of ZNPP is enough to observe asignificant improvement in thermal bondability of the fibres andmechanical properties of the non-woven fabrics. As a consequence, thespinnability of the fibres produced using miPP/ZNPP blends in accordancewith the invention is not significantly modified as compared to knownmiPP fibres.

[0046] The fibres produced in accordance with the invention may beeither bi-component fibres or bi-constituent fibres. For bi-componentfibres, miPP and ZNPP are fed into two different extruders. Thereafterthe two extrudates are spun together to form single fibres. For thebi-constituent fibres, blends of miPP/ZNPP are obtained by: dry blendingpellets, flakes or fluff of the two polymers before feeding them into acommon extruder; or using pellets or flakes of a blend of miPP and ZNPPwhich have been extruded together and then re-extruding the blend from asecond extruder.

[0047] When the blends of ZNPP/miPP are used to produce fibres inaccordance with the invention, it is possible to adapt the temperatureprofile of the spinning process to optimise the processing temperatureyet retaining the same throughput as with pure miPP. For the productionof spunlaid fibres, a typical extrusion temperature would be in therange of from 200° C. to 260° C., most typically from 230° C. to 250° C.For the production of staple fibres, a typical extrusion temperaturewould be in the range of from 230° C. to 330° C., most typically from280° C. to 310° C.

[0048] The fibres produced in accordance with the invention may beproduced from miPP/ZNPP blends having other additives to improve themechanical processing or spinnability of the fibres. The fibres producedin accordance with the invention may be used to produce non-wovenfabrics for use in filtration; in personal care products such as wipers,diapers, feminine hygiene products and incontinence products; in medicalproducts such as wound dressings, surgical gowns, bandages and surgicaldrapes; in protective covers; in outdoor fabrics and in geotextiles.Non-woven fabrics made with the ZNPP/miPP fibres of the invention can bepart of such products, or constitute entirely the products. As well asmaking non-woven fabrics, the fibres may also be employed to make aknitted fabric or a mat. The non-woven fabrics produced from the fibresin accordance with the invention can be produced by several processes,such as air through blowing, melt blowing, spun bonding or bonded cardedprocesses. The fibres of the invention may also be formed as a non-wovenspunlace product which is formed without thermal bonding by fibres beingentangled together to form a fabric by the application of a highpressure-fluid such as air or water.

[0049] The present invention will now be described in greater detail byreference to the following non-limiting examples.

EXAMPLE 1

[0050] In accordance with this example, the properties of a non-wovenproduct composed of polypropylene fibres incorporating at least 80 wt %miPP with the remainder being znPP were compared to fibres composed ofpure miPP. Thus the pure miPP had an MFI of 32 g/10 mins and a Mw/Mnratio of 3. The znPP had an MFI of 12 g/10 mins and an Mw/Mn ratio of 7.Three blends, hereinafter called Poly 1, 2 and 3, of the miPP and theznPP with respective weight ratios of 80 wt % miPP/20 wt % znPP, 90 wt %miPP/10 wt % znPP and 95 wt % miPP/5 wt % znPP were produced. Fibreswere made both of the blends Poly 1, 2 and 3 and of the pure miPP. Thefibres were spun by a long spin process, with the polymer temperature inthe spinnerets being 280° C. The fibre titre after spinning was 2.3 dtexand the fibre titre after drawing was 2.1 dtex. The fibres weretexturised and cut after the drawing step. They were then stored inbales of 400 kg for 10 days. The fibres were then subjected to cardingand bonding at a speed of 110 m/minute. Thereafter, non-woven productshaving a weight of 20 g/m² were produced by thermal bonding. The thermalbonding temperature and the mechanical properties of the non-wovensthereby produced for the Poly 1, 2 and 3 and the pure miPP are shown inTable 2.

[0051] It may be seen from Table 2 that the mechanical properties of thenon-woven thermally bonded product of Poly 1, 2 and 3 are greater thanthat for pure miPP at corresponding thermal bonding temperatures.

EXAMPLE 2

[0052] In accordance with this example, various blends of znPP and miPPwere made and the compositions of the blends are specified in Table 3.

[0053] The miPP had an MFI of 13 g/10 min. The znPP was the same as thatemployed in Example 1. The blends were prepared by dry blending pelletsof the components and pouring the dry blend into the feeder of theextruder immediately after blending. Fibres were then produced from theextruded blend. The fibre was produced using a spinneret having 224holes with a length/diameter ratio of 8/0.8. The extrusion temperaturewas 285° C. with quenching air at 15° C. at a pressure of 50 Pa. Thetemperature of the drawing godets was 80° C. For each blend, fibres wereproduced under the conditions of take-up at 1600 m/min followed bydrawing with a draw ratio (SR) of 1.3. The throughput per hole wasadjusted to keep the fibre titre at around 2.5 dtex.

[0054] Table 3 shows the titre, the fibre tenacity at 10% elongation,the elongation at maximum drawing force, the fibre tenacity at maximumdrawing force (sigma@max) . FIGS. 3 and 4 are graphs showing therelationship between the elongation at maximum drawing force and thefibre tenacity at maximum drawing force, respectively, with respect tothe amount of miPP in the blend.

[0055] Table 4 shows the titre, the fibre tenacity at 10% elongation,the elongation at maximum drawing force, the fibre tenacity at maximumdrawing force (sigma@max) for fibres produced as described here-abovebut without drawing.

[0056] It may be noted that for a blend having greater than 80 wt % miPPin the blend of znPP/miPP, the elongation at maximum drawing force andthe fibre tenacity at maximum drawing force are substantially increasedwith respect to lower miPP amounts. Thus by adding miPP to a znPP/miPPblend in an amount of at least 80 wt % miPP, the mechanicalcharacteristics of the fibre are improved, in particular the fibreelongation and tenacity, and in addition, as shown in Example 1, thecharacteristics of the bonding of the fibres to form thermally bondednon-wovens are improved.

EXAMPLE 3

[0057] This example demonstrates the increase in bulk or softness ofpolypropylene fibres by incorporating into the blend of znPP/miPP anamount of sPP.

[0058] When polypropylene fibres are laid on a flat surface, such as aglass plate, the morphology of the fibre, in particular its degree ofstraightness or, conversely, its degree of waviness, is an indication ofthe bulk of the fibre. The fibre, which can be examined by opticalmicroscopy, can be seen to have a wavy or substantially sinusoidalmorphology, with increased waviness (i.e. a reduced pitch between peaksof adjacent waves) corresponding to increased bulk or softness of thefibre.

[0059] When sPP was added to a polypropylene homopolymer in an amount upto 15 wt %, it has been found that the distance between two peaks of thewavy surface decreases, in turn meaning that the bulk or softness of thefibres increases. For example when 5 wt % sPP was blended into aZiegler-Natta polypropylene homopolymer, the distance between the peakswas 5.1 mm whereas when 15 wt % sPP was blended into the samepolypropylene, the distance between the peaks was around 4 mm. Thisdemonstrates that the bulk or softness of the fibres was increased withincreasing amount of sPP in the base polypropylene. TABLE 1 ZNPP sPPmiPP1 miPP2 MI₂ 14 3.6 32 13 Tm ° C. 162 110 and 127 148.7 151 Mn kDa41983 37426 54776 85947 Mw kDa 259895 160229 137423 179524 Mz kDa1173716 460875 242959 321119 Mp kDa 107648 50516 118926 150440 D 6.1 4.32.5 2.1

[0060] TABLE 2 Thermal Bonding Max Force Elong @ break Max Force Elong @break Temperature Mach. Dir Mach. dir Trans dir Trans dir Blend (° C.)(N/5 cm) (%) (N/5 cm) (%) Poly 1 142 36 95 10 105 Poly 1 148 28 62 14133 Poly 2 142 32 90 11 105 Poly 2 148 28 50 12 117 Poly 3 142 29 50 1080 Poly 3 148 26 40 11 40 Pure miPP 142 13 25 6 20 Pure miPP 148 12 20 620

[0061] TABLE 3 Take-up: 1600 m/min followed by drawing (SR = 1.3) wt %wt % Titre Tenacity @ 10% Elong @ Sigma @ max znPP miPP (dtex) (cN/tex)max (%) (cN/tex) 100 0 2.6 9.6 407 20.0 80 20 2.6 9.2 379 19.8 60 40 2.69.2 397 21.5 40 60 2.6 8.9 339 20.7 20 80 2.6 8.8 281 22.3 15 85 2.5 7.8352 23.9 10 90 2.5 8.2 322 26.7 5 95 2.5 8.6 312 29.3 2 98 2.5 9.2 25631.4 0 100 2.6 11.5 164 32.3

[0062] TABLE 4 Direct Take-up: 1600 m/min wt % wt % Titre Tenacity @ 10%Elong @ Sigma @ max znPP miPP (dtex) (cN/tex) max (%) (cN/tex) 100 0 2.66.8 435 14.8 80 20 2.6 6.5 513 15.9 60 40 2.5 6.6 456 16.4 40 60 2.6 6.3461 17.1 20 80 2.6 6.1 443 20.3 15 85 2.2 5.8 485 18.9 10 90 2.4 5.8 42420.4 5 95 2.6 5.4 496 20.5 2 98 2.6 5.5 363 24.0 0 100 2.6 6.2 285 27.9

1. A polypropylene fibre including at least 80% by weight of a first isotactic polypropylene produced by a metallocene catalyst, and from 5 to 20% by weight of a second isotactic polypropylene produced by a Ziegler-Natta catalyst.
 2. A polypropylene fibre according to claim 1 including from 90 to 95% by weight of the first isotactic polypropylene and from 5 to 10% by weight of the second isotactic polypropylene.
 3. A polypropylene fibre according to claims 1 or 2 wherein the first polypropylene is a homopolymer, copolymer or terpolymer of isotactic polypropylene or a blend of such polymers.
 4. A polypropylene fibre according to claim 3 wherein the first polypropylene has a dispersion index (D) of from 1.8 to
 4. 5. A polypropylene fibre according to claim 3 or claim 4 wherein the first polypropylene has a melting temperature in the range of from 80 to 161° C.
 6. A polypropylene fibre according to any foregoing claim wherein the first polypropylene has a melt flow index (MFI) of from 1 to 2500 g/10 mins.
 7. A polypropylene fibre according to any foregoing claim wherein the second polypropylene has a dispersion index of from 3 to
 12. 8. A polypropylene fiber according to any foregoing claim wherein the second polypropylene has a melting temperature in the range of from 80 to 169° C.
 9. A polypropylene fibre according to any foregoing claims further comprising up to 15% by weight of a syndiotactic polypropylene (sPP).
 10. A polypropylene fibre according to claim 9 comprising up to 10% by weight of a syndiotactic polypropylene (sPP).
 11. A polypropylene fibre according to claim 10 wherein the sPP is a homopolymer, a random copolymer, a block copolymer or a terpolymer or a blend of such polymers.
 12. A polypropylene fibre according to claim 10 or claim 11 wherein the sPP has a melting temperature of up to about 130° C.
 13. A fabric produced from the polypropylene fibre according to any foregoing claim.
 14. A product including a fabric according to claim 13, the product being selected from a filter, personal wipe, diaper, feminine hygiene product, incontinence product, wound dressing, bandage, surgical gown, surgical drape, geotextile, outdoor fabric and protective cover. 